Get current panel page html for use in 'pdf_using_mpdf_api($html)'

Hi, sbilde!
You can use the code below to get the html content of your panel:

function mymodule_generate_panels_content($panel_machine_name, $node) {
  $task = page_manager_get_task($panel_machine_name);

  // Load the node into a context.
  ctools_include('context');
  ctools_include('context-task-handler');
  $contexts = ctools_context_handler_get_task_contexts($task, '', array($node));

  $output = ctools_context_handler_render($task, '', $contexts, array($node->nid));
  if ($output !== FALSE) {
      return drupal_render($output['content']);
  }
  else {
    drupal_set_message(t('There is no content for that node!'), 'warning');
    drupal_goto(urlencode('node') . '/' . $node->nid);
    return;
  }
}

After that you can generate pdf file by calling pdf_using_mpdf_api($html, $filename) function.

If you need to add some more css to style your pdf exactly like according node's page, you should apply my patch from here, and then implement hook in your module like this:

function mymodule_mpdf_document_alter(&$mpdf_object) {
  // Setting CSS stylesheet to PDF.
  global $theme_path;
  $stylesheet_content = file_get_contents($theme_path . '/css/global.css');
  $mpdf_object->WriteHTML($stylesheet_content, 1);
}